Testing apparatus and method for composite articles

ABSTRACT

A testing apparatus for a composite material includes a base for holding the composite article, a load cell for placing a selected load on a portion of the composite article, and a displacement measuring device for measuring the amount of displacement for a selected load. In operation, a composite article is placed in a testing apparatus, a selected load is placed on the composite article, and the displacement of the composite article is measured.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority based upon co-pending U.S. applicationSer. No. 10/952,483 filed Sep. 28, 2004 which claims priority to thenco-pending application Ser. No. 10/842,833 filed May 11, 2004 whichclaims priority to Application Ser. No. 60/470,540 filed May 14, 2003.

FIELD OF THE INVENTION

The present invention relates to the field of testing and moreparticularly to a testing apparatus and method for composite articles.

BACKGROUND OF THE INVENTION

For several decades now, products have been made of composite materials.In the early days, many articles were made of fiberglass. Boat hullswere made of fiberglass. Wooden hulled boats were also covered byfiberglass to reduce or eliminate leaks and to lengthen the life of ahull. More recently, composites have been used for other purposes. Forexample, some bats are now made from 20 composite materials. For manyyears, baseball bats and softball bats were made of wood.

Softball bats made of composites have several advantages. Among theadvantages is the capability to design and manufacture a bat havingconsistent performance. Another advantage is that source of compositematerials for the manufacture of baseball bats and softball bats isreadily available. Baseball bats and softball bats made of naturalmaterial, such as ash or very hard pine, are prone to inconsistency and,sadly, the sources of such woods are becoming increasingly scarce. Oneproblem associated with softball bats and baseball bats made ofcomposite materials is the lack of a test for categorizing theperformance of various composite softball bats or baseball bats.

Another problem is that it is difficult to determine if a softball batmade of a composite material has been modified to enhance performance.In all 5 walks of life, some individuals seek an unfair advantage. Somesoftball players and baseball players are no different and will modify abat to gain an unfair advantage. To date, there does not appear to be atest to determine if a softball bat or baseball bat has been modified.In addition there does not appear to be a testing apparatus that isportable to allow field testing.

A softball or baseball bat formed of composite material also may wearand the performance characteristics may change over time. In the past,there has not been a testing apparatus to monitor these changes.

SUMMARY OF THE INVENTION

A softball bat is made entirely out of composite material. The mainportion of the bat includes a substantially tubular hiring surface and ahandle. A composite sleeve is added within the hitting surface. Thesleeve is made of composite material. The hitting surface is also madeof composite material.

Advantageously, the composite material has a lower density than 20metals used to make bats, such as aluminum or titanium. As a result,more material can be used resulting in a more durable bat for a givenweight of bat. The composites also have a higher strength than aluminumand titanium and their alloys. Therefore, a stronger bat can beproduced. In addition, the composite does not dent and therefore moreenergy is transferred to the ball. There is less, if any, energy wastedon denting the bat or the inner sleeve. Therefore, the inventive bathits farther than a wooden or metal bat or bat having metal parts. Theinventive bat is made entirely of composite material. Composite materialcan be made either more stiff or more flexible than a metal bat. Thedesign parameters of a composite are more flexible so that either a moreflexible or stiffer bat can be formed by varying the engineeringparameters. The additional flexibility in using composite materialallows designers to form bats with selected performance characteristics.If the bat is made to be more flexible, the inventive bat has adurability advantage since the bat does not dent and begin the somewhatslow process of failing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a ball bat, with a portion of thetubular hitting surface broken away to show a sleeve according to thepresent invention.

FIG. 2 is a schematic view of one embodiment of a testing apparatus formeasuring the flexibility of a bat.

FIG. 3 is flow chart detailing the use of the testing apparatus of theembodiment of the invention shown in FIG. 2.

FIG. 4 is a schematic view of another testing apparatus for measuringthe flexibility of a bat, according to another embodiment of thisinvention.

FIG. 5 is an exploded perspective view of a set of sheetspre-impregnated fibers and a mandrel used to form the inner sleeve ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings, which form a parthereof, and in which are shown by way of illustration specificembodiments in which the invention may be practiced. It is to beunderstood that other embodiments may be utilized and structural changesmay be made without departing from the scope of the present invention.

The invention described in this application is useful with allmechanical configurations of bats including softball bats and baseballbats. FIG. 1 is an exploded view of one type of a bat 100 having asubstantially tubular hitting surface 110 and a handle 100. The ball bat100 is made of composite material. The main portion of the bat 100includes a substantially tubular hitting surface 110. A handle 120 isattached to the hitting surface. The handle 120 and barrel are integralin the bat shown in FIG. 1. It should be noted that the bat could beformed of a separate handle 120 and tubular hitting surface or barrel110. The tubular hitting surface 110 and the attached handle 120 formthe body 140 of the bat. The diameter of the handle 120 is less than thediameter of the tubular hitting surface 110 and therefore the body 140of the bat includes a tapered portion 114 that is positioned between thehandle 120 and the tubular hitting surface 110. The bat may include a 10sleeve 112 is within the body 140 of the bat and more specificallywithin the tubular hitting surface 110. As mentioned above, the ball bat100 includes one or more portions made a composite material thatincludes a fiber and a resin. The fibers can be made of Kevlar,graphite, carbon, boron, rayon, nylon, fiberglass, other plastics orother polymer materials. Graphite nano tubes may also be used. The resinor binding material may include thermosetting resin systems, epoxies,ceramics, or thermoplastics. The fibers are impregnated with a resin toform a composite material. A plug 130 is at a free end of the hittingsurface 110.

The amount flexibility of a bat is linked to characteristics offavorable bat performance. It should be noted that some favorableperformance 20 characteristics may come at the expense of otherfavorable performance characteristics. In short, there may be a tradeoff in terms of performance characteristics. An example of this is thatthe life of a softball bat is generally shortened as the flexibility ofthe bat increases. In other words, a more flexible, long-hittingsoftball bat will typically have a shorter useful life than a lessflexible, shorter-hitting softball bat.

FIG. 2 is a schematic view of one embodiment of a testing apparatus 200for measuring the flexibility of a bat 210. The testing apparatus 200includes a base 220 that includes an upright 222 attached to the baseand a datum 224 also attached to the base 220. The datum 224 is spacedaway from the upright 222.

Attached to the upright 222 is a load arm 230. The upright 222 has anopening 223 therein. The load arm 230 is attached to the upright by apivot pin 232. The pivot pin 232 allows the attached end of the load arm232 to pivot about the opening 223 in the upright 222. A dial indicator240 is positioned between the upright 222 and the datum 224 and near theload arm 230. The dial indicator 240 is placed so that when the bat 210is placed in the testing apparatus 200, the dial indicator 240 contactsthe bat 210 near the load arm 230. Positioned at or near the free end ofthe load arm 230 is a load cell 250. The load cell 250 produces aspecified load on the free end of the load arm 230. The distance betweenthe pivot point at the center of the pivot pin 232 and the point on theload arm 230 where the load cell 250 acts is designated as dimension“A”. The distance between the pivot point at the center of the pivot pin232 and the point where the load arm 230 contacts the bat 210 isdesignated as dimension “B”. The distance between the end of the base220 nearest the uptight 222 and the datum 224 is designated as dimension“C”. Of course, different embodiments of the testing apparatus 200 havedifferent dimensions (A, B, C). In the embodiment shown in FIG. 2, thedimensions are as follows:A=17 9/16 inchesB=2¾ inchesC=4 inches

Using the testing apparatus 200 described in the example above, batshaving a flexibility value above 600 have favorable performancecharacteristics. Bats having a flexibility in the range of 550 to 1250units also have favorable performance characteristics.

In operation, the testing apparatus 200 is used to test a bat, such asbat 210, for flexibility. Testing the bat requires a test procedure 300.The test procedure 300 includes placing the bat in the testingapparatus, as depicted by reference numeral 310. The bat 210 is placedon the base 220 and in contact with datum 224. Next, the load cell 250applies 10 pounds of force at load end or free end of the load arm 230,as depicted by reference numeral 312. The dial indicator 240 and theload cell 250 are each zeroed, as depicted by reference numeral 314.Next, the load cell 250 applies 60 pounds of force at load end or freeend of the load arm 230, as depicted by reference numeral 316. The dialindicator 240 is then read to determine the amount of deflection of thebat at the point or in the area where the load arm 230 contacts the bat210, as depicted by reference numeral 318. This procedure is repeated anumber of times around the circumference of the bat 210, as depicted byreference numeral 320. The average value is then used to determine anumber to indicate the flexibility of the bat 210, as depicted byreference numeral 322. A flex number for each test may be determined. Afixed load may be placed on the softball bat and the average deflectionmay also be used to determine a flex number.

One example of a calculation of such a flex number includes dividing theload placed on the arm by the load cell 250 by the amount of deflectionindicated by the dial indicator 240. In this example, the load of 60 lbsis divided by the deflection in inches (60 lbs./0.0575″=1043 lbs./inchor 1043 Flex) to yield a flex indication number of 1043. It iscontemplated that the flex indication number could be recalibratedthereby producing a new scale. For example, the actual load at the pointwhere the lever arm contacts the softball bat can be used to determinethe lbs./inch of flex in the bat. It is further contemplated that othertesters or testing 20 apparatus could be used to determine flexibilityof the bat 210 under test without departing from the spirit of thisinvention.

FIG. 4 is a schematic view of another embodiment of a testing apparatus400 for measuring the flexibility of a bat 210.

A testing apparatus 400 includes a C-shaped element 420. The C-shapedelement 420 includes two arms having ends that hold a first fastener 426and a second fastener 430. The first fastener 426 threads into one endof the C-shaped element 420. The fastener 426 includes a first end 428which includes an upset end and a second end which includes a base 422.The base 422 includes a depression or feature 424 used to hold a bat410. Specifically, the feature or depression 424 is shaped to hold thebarrel of a bat 410. The base 422 is attached to the first fastener 426.The fastener 426 is used to move the plate 422 into engagement with thebat 410 by turning the fastener 426 and specifically the head of thefastener 428. In this particular embodiment, the head of the fastener428 is turned until it is finger tight which assures that the bat 410 isengaged with the base 422 and specifically with the depression orfeature 424 within the base 422. The other end of the C-shaped member420 carries fastener 430. Fastener 430 is threadably engaged with theother end of the C-shaped member 420. A spring 432 having a specifiedforce constant is also engaged with the other end of the C-shaped unit420. The spring is attached to a load beam 434. While the spring iscompressed or when the spring is fully compressed, a fixed load isplaced on the bat 410 at a point or an edge depicted by referencenumeral 450. It should be noted that the load beam 434, as shown in thisembodiment, is essentially a flat plate which is used to contact or loadthe bat or side of the bat 410. It is further contemplated that othergeometric shapes could be added to the load beam such as a point orother geometric shape. A dial indicator 440 is attached to the load beam434. The fastener 430 is tightened until the spring is moved through aspecified distance thereby loading the load beam 434 to a specific orspecified amount of force. The force can be determined by knowing theforce constant of the spring and turning the fastener 430 to compressthe spring a 20 selected amount, thereby producing the selected force.The dial indicator 440 indicates the amount of displacement on thesurface of the bat 410 or displacement of the bat for the specifiedload.

It should be noted that in other embodiments of this invention, adifferent arrangement can be used. For example, it may be advantageousto place a shock load on the bat 410. Therefore, the spring 432 wouldinitially be loaded and suddenly released, thereby forcing the load beam434 into contact momentarily with the bat 410. The force would be animpulse force or a shock load that would replicate the forces placed ona bat when a ball is hit with the bat 410. The dial indicator 440 can beused to measure the amount of deflection in either the steadyapplication of force embodiment discussed above or for the embodimentwhere the bat 410 is shock loaded to replicate a hit on a ball with thebat 410.

Now turning to FIG. 5, a test process 500 will be discussed. Testprocess 500 includes placing the bat in the test apparatus, as depictedby reference numeral 510. Specifically, the bat 410 is placed in thedepression 424 of tire base 422. Next, the first fastener 426 is fingertightened, as depicted by reference numeral 512. The dial indicator 440is zeroed as is the load ceil, as depicted by reference numeral 514. Aforce is then applied at point 450 by tightening the second fastener 430and causing the spring 432 to move through a fixed distance. This causesthe spring 432 to place a fixed force on the bat through the load beam434, as depicted by reference numeral 516. Next, the amount ofdeflection at the point 450 where the load beam contacts the bat isdetermined by reading the dial indicator 440, as depicted by referencenumeral 518. Once this is completed, a flexibility number, in terms ofthe pounds per inch of deflection, can then be determined. The test isthen repeated at several different points along the bat, as depicted byreference numeral 520. In a preferred embodiment, the test is conductedat several points along the barrel of the bat. The various flex numbersare then averaged or added up to determine an overall flex number.

Advantageously, either of the embodiments of the testing apparatus 200,400 are portable so that an umpire or a testing organization could testcomposite articles such as bats 210, 410 in the field. It iscontemplated that the flex numbers associated with a particular batcould be placed upon the bat or a directory including all the flexnumbers for various softball bats could be placed in either a databaseor a book form. Softball bats or other composite articles could then betested in the field to determine if the flexibility number associatedwith the bat is within an acceptable range of the flexibility numberassociated with the bat at manufacture. Another formulation of the testmight be to set a threshold for flexibility and a threshold number orflexibility number in pounds per inch of deflection over which a batwould no longer qualify or be certified by a certification organization.In this manner, the testing could be random or could be carried out atthe request of any person on the field to determine if a particular bator composite article is within specifications and can be used in atournament. In this manner, composite articles such as softball batsthat have been modified and are now outside the specification of thecertification organization can be found in the field. Furthermore, batsor composite articles that have been used and are no longer within speccan also be found in the field. In particularly important games or inparticularly important circumstances, all composite articles such assoftball bats can be tested prior to the beginning of a contest.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reviewing the abovedescription. The scope of the invention should, therefore, be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

1. A method of testing a composite article comprising: applying a staticload to the hitting area on the composite article; measuring thedisplacement of the composite article; wherein applying a static load onthe composite article includes loading the composite article within theelastic limit of the composite article; and wherein measuring thedisplacement includes measuring the displacement at the plurality ofareas associated with the composite article, the method furthercomprising averaging the amount of displacement for each of themeasurement at the plurality of areas.
 2. The method of claim 1 whereinapplying a static load on the composite article includes loading aportion of a bat.
 3. The method of claim 2 wherein applying a staticload to a portion of the bat includes loading a portion of a hittingsurface of the bat.
 4. The method of claim 2 wherein applying a staticload to a portion of the bat includes placing a load on a plurality ofareas associated with a hitting surface of the bat.
 5. The method ofclaim 4 wherein measuring the amount of displacement includes measuringthe amount of displacement at the plurality of areas associated with thehitting surface of the bat.
 6. The method of claim 1 wherein applying astatic load on the composite article includes loading the compositearticle without denting the hitting area of the composite article. 7.The method of claim 1 further comprising dividing the static load placedon the article by the measured displacement to yield a numberrepresenting flexibility of the composite article.
 8. A method oftesting a composite article comprising: applying a static load to thehitting area on the composite article; measuring the displacement of thecomposite article; wherein applying a static load on the compositearticle includes loading the composite article within the elastic limitof the composite article; wherein applying a static load on thecomposite article includes loading a portion of a bat; wherein applyinga static load to a portion of the bat includes placing a load on aplurality of areas associated with a hitting surface of the bat; furthercomprising dividing the load placed on the bat by the measureddeflection to yield a number representing flexibility of the bat;determining a number representing flexibility at a plurality of pointson the bat; and averaging the determined flexibility numbers.